The present invention relates to a semiconductor device fabrication method, more specifically a semiconductor device fabrication method which can decrease intra-wafer plane dispersions of the film thickness of a gate insulation film.
Recently, digitization, band broadening, media multiplexing and formation of networks have been advanced. Such changes in the commercial environments require more speedup, higher integration, higher functioning, etc. of semiconductor devices.
For the more speedup, the higher integration, etc., recently the gate insulation films of the transistors of logic circuit (high speed logic circuits) are increasingly thinned. In logic circuits of a 0.13 μm design rule, the film thicknesses of the gate insulation films have been decreased down to about 1.75 nm.
On the other hand, as a technique for realizing the higher functioning, semiconductor devices having a plurality of functions mounted on one and the same substrates are noted. This technique is called SoC (System on Chip). For example, semiconductor devices having flush memories and logic circuits mounted on one and the same substrates, semiconductor devices having DRAMs and logic circuits mounted on one and the same substrates, etc. are proposed.
Following references disclose the background art of the present invention.
[Patent Reference 1]
Specification of Japanese Patent Application Unexamined Publication No. Hei 10-189565
However, in the semiconductor devices flush memories and logic circuit mounted on one and the same substrates and the semiconductor devices having DRAMs and logic circuits mounted on one and the same substrates, the film thicknesses of the gate insulation films of the transistors of the logic circuits have had large dispersions. That is, in forming the gate insulation film on the surfaces of the semiconductor wafers, the film thicknesses of the gate insulation film have been largely varied in plane of the substrates. Accordingly, it has been difficult to provide semiconductor devices having stable electric characteristics.